1. Field of the Invention
The present invention relates to a vibration damping mount for installation between a sub-frame of a vehicle suspension device and a vehicle body.
2. Description of Related Art
It is well known that a vibration-damping sub-frame structure having a vibration-damping mount disposed between a sub-frame of a vehicle suspension device and a vehicle body is effective for reducing vehicle vibration and noise. The vibration-damping mount generally includes an inner cylindrical sleeve and outer cylindrical sleeve which are coaxially arranged with each other. A vibration-damping rubber body is disposed between the inner cylindrical sleeve and outer cylindrical sleeve, and is joined thereto. The vibration-damping mount thus-arranged is installed in the vehicle by securing the inner cylindrical sleeve to the vehicle body with bolts, and fitting the outer cylindrical sleeve into an opening provided in the sub-frame. One axial end of the outer cylindrical sleeve normally bends radially outwardly to define a flange. An annular rubber stopper is formed on the flange such that an end edge of the annular rubber stopper abuts a stopper plate which is secured to one axial end of the inner cylindrical sleeve.
The above-described conventional vibration-damping sub-frame structure reduces vehicle vibration and noise, but degrades stability and controllability. This disadvantage is caused by a relative displacement occurring in the vibration-damping mount between the outer cylindrical sleeve secured to the sub-frame and inner cylindrical sleeve secured to the vehicle body. This displacement is due to a force exerted from the suspension to the sub-frame. In particular, the relative displacement occurring in the vertical direction of the vehicle affects the vehicle stability and controllability.